Why there are high frequency spikes in the instantaneous frequency variation vs time curve of a faulted phase current ?

I am working on the analytic signal concept for observing the frequency variation in the faulted phase current waveform in MATLAB/Simulink model. In MATLAB/Simulink model, I have used analytic signal block and hilbert's transform method to calculate the real and imaginary components of the faulted phase current. After that I have used the data for real and imaginary components of the faulted phase current to calculate the magnitude, phase, and instantaneous frequency. When I plotted the curve between the instantaneous frequency variation vs time for the faulted phase current, I observed that there are high frequency spikes in the curve. What can be the reason and what is this phenomena called ?

Answer 1

[Constantino Carlos Reyes-Aldasoro]

It is very different to answer this question on the abstract, please add more details and figures preferably to be able to help.